Conventionally, a variable valve mechanism is known in which the lift amount, the working angle, and the open/close timing of the valve are controlled by using links. For example, the variable valve mechanism 200 in Japanese Patent Application Publication No. JP-A-11-324625, shown in FIG. 25, is provided with a camshaft 201 that is rotated by the crankshaft of an internal combustion engine. A rotating cam 202 is fastened to the camshaft 201 so as to rotate integrally therewith, and at the same time, a drive arm 204 that drives a valve 210 via a valve lifter 203 is supported so as to be able to rotate relatively thereto.
A swing arm 206 is supported by a variable cam 207 on a control shaft 205 that is parallel to the camshaft 201. The input end of the swing arm 206 is linked to the rotating cam 202 via a ring-shaped link 208, and the output end of the swing arm 206 is linked to the drive arm 204 via a rod-shaped link 209. In addition, the control shaft 205 is driven by an actuator, the swing arm 206 is shifted due to the eccentric rotation of the variable cam 207, and the initial position of the drive arm 204 with respect to the rotating cam 202 thereby changes.